Pumbaa is a warthog the size of a lion cub with smooth red fur that is slightly darker on his underbelly. He has a large head, a rounded lower jaw, and jutting cheeks. He has a smoothed-back mane of black hair running alone his head and neck, and a black tail tuft. His nose is light pink, with large, circular nostrils. Two ivory-colored tusks jut from his upper jaw, and his small eyes have yellow sclerae. Pumbaa's inner ears are dark pink.
Pumbaa is a jolly, kind, funny, benevolent, fun-loving, happy-go-lucky, and enthusiastic warthog with a deep heart, though he is quick to panic when something goes wrong. He shows deep concern for Bunga when he is told of his future role in the Lion Guard, though soon comes to accept it. Unlike Timon, Pumbaa's intentions are always kind and thoughtful. However, he is very emotional, and not very helpful in a difficult situation.
Pumbaa, along with Timon, found Simba, who fled his home. They raised him to eat grubs and live a worry-free lifestyle. When Simba reached adulthood and went back to Pride Rock to reclaim his title as king from Scar, Pumbaa and Timon went with him to help fight. The battle was a success, Simba became king, and Pumbaa and Timon have stayed in the Pride Lands ever since.
One day, he and Timon were on their way to get some Utamu grubs, when they came across baby Bunga, who showed great interest in joining them. Although Pumbaa was keen to keep him, Timon was not so enthusiastic and made a couple of attempts to get him to leave. When Bunga came back with the Utamu grubs, Timon finally agreed with Pumbaa, and the two raised him.
Timon and Pumbaa receive a visit from Bunga, who is excited to tell them of his new role in the Lion Guard. Both are at first largely concerned about this, with Pumbaa's fear leaning towards possible danger that he could come into contact with. After Bunga talks to them both, they come to accept his new role.
Timon and Pumbaa are informed of Bunga's odor problem by Ono. However, they don't believe there's anything wrong with Bunga's scent, and that he's perfectly fine just the way he is. They argue with Ono over Bunga's smell.
After Bunga hears Rafiki saying that honey badgers were the Pride Lands smartest animals, the young honey badger raced off to tell his uncles. Pumbaa and Timon both spread the word, causing many Pride Landers to come to Bunga seeking advice. When Kion and the Guard approach Timon and Pumbaa, they sing Bunga the Wise together, with Bunga eventually joining in.
Later, Pumbaa is seen parading through the Pride Lands with Bunga, Timon, and many other Pride Landers. When Bunga's temporary dam breaks, Pumbaa flees to high ground with Timon.
After Bunga is bitten by Ushari, Ono goes to tell Timon and Pumbaa. By the time the Lion Guard gets Bunga to Rafiki, Pumbaa is already panicky, and he begins to sob as Bunga dramatically acts as though he is dying. Pumbaa is shocked when Rafiki says that he plans to do nothing about Bunga's wound, but when Rafiki reveals that honey badgers are immune to snakebites, Pumbaa is delighted. Timon invites the Lion Guard from to dinner at Hakuna Matata Falls, but they all deny. Upon hearing from Fuli that female cheetahs prefer to hunt alone, Timon insists on inviting Fuli, and she reluctantly accepts.
At dinner with Fuli, Timon offers her a wide variety of bugs. Fuli is disgusted, but Timon decides that the issue is that Fuli is not being engaged in dinner conversation, and tosses the bug-covered leaf behind him. Pumbaa promptly devours it, and Timon attempts to chat with Fuli, but ends up marveling at how soft her fur is, even inviting Pumbaa to come feel it. Pumbaa agrees that her fur certainly is soft. Fuli says that she doesn't like it when others touch her fur, and eventually makes a quick retreat.
During the search for the rare Utamu grubs, Bunga explains to Kion, Beshte and Ono how he met his uncles Timon and Pumbaa. While Timon and Pumbaa were searching for the Utamu grubs, Bunga had caught sight of them and immediately wanted to be friends. Pumbaa wanted to keep Bunga right away, and eventually convinced Timon to adopt the young honey badger. Bunga is bitterly disappointed that he must return to his uncles without the Utamu grubs that day, but neither Timon or Pumbaa show any signs of disappointment when Bunga arrives. They explain to Bunga that only reason they shared the Utamu grubs was to celebrate their friendship. Much to Bunga's surprise, however, the grubs landed near them anyway and the trio is able to share a loving hug before diving into the grubs.
The Lion Guard has sought out Timon's assistance in some underground caverns where they are searching for Bunga and Simba, and Pumbaa comes along. He and Timon are very distressed and worried about Bunga and Simba, and Pumbaa remarks on the cruelty of fate. Crying, he expresses the thought that they'll never get out of the caverns alive, and Ono points out that the entrance to the cave is visible. Eventually, he and Timon compose themselves and they move through the caverns. Pumbaa tells Kion that he'll understand when he has kids of his own, or more specifically when a lost lion or honey badger wanders into his corner of the world. Suddenly, he hears the sound of Bunga and Simba's voices.
Pumbaa and Timon rush forward, and Pumbaa assures Bunga and Simba that they're coming. They at first head in the wrong direction and crash, then turn around and run through a different tunnel. Upon seeing Bunga and Simba, Pumbaa is very glad that they're all right. He watches as Simba leaps over a gorge that separates them with Bunga on his back, then approaches Simba and begins kissing him enthusiastically. Timon accuses Pumbaa of being worried that they'd never find their kids, and Pumbaa apologizes, declaring that he should have remembered hakuna matata.
Back above ground, Pumbaa sings Hakuna Matata with the Lion Guard and the royal family for Ma Tembo's Herd, with Simba declaring them as his family.
Timon and Pumbaa are seen briefly during Life in the Pride Lands. As Beshte passes by whilst giving Ajabu a tour of the Pride Lands, Pumbaa is seen floating in the water with Timon resting on his stomach.
Pumbaa is mentioned when Laini and the galagos come rushing to the Lion Guard, despite being told to stay in Hakuna Matata Falls. Laini mentions hearing a noise which, to her, sounded like a raspberry. Bunga decides it was his Uncle Pumbaa, and once Laini mentions a terrible smell, Ono confirms it was Pumbaa. Beshte mentions that Pumbaa won't hurt the galagos, but she wishes to stay with the Guard regardless.
Timon and Pumbaa overhear Kion dismissing claims of the Zimwi being sighted. But Pumbaa is adamant that Timon is the only animal to ever survive an encounter with the being. Though it is soon revealed that it is actually his Ma's cousin's friend who knew an ox who told him that he ran into The Zimwi and got eaten. Kion questions how the ox could tell the tale if he was eaten, and Pumbaa marks it as a good question, turning to Timon who tells the cub that he'd have to ask the ox. Timon frightens the youngsters by telling them that there's nothing they can do, so Kion calls for the Guard to solve the mystery themselves, with Bunga eager to get going. Pumbaa cries softly, worried about how brave Bunga is.
Later, when Beshte is practicing his bellowing for The Bellow Fellows, Bunga mentions that he sounds just like his uncle Pumbaa at one stage.
Bunga mentions Pumbaa when singing Stand Up, Stand Out. He explains to Ono how everyone knows his uncle Pumbaa because of his impressive flatulence. As he does, he points out a painting on the walls of The Lair that depicts Pumbaa and Timon. Bunga later mentions that his uncles considered Scar to be the worst lion in the world.